<!DOCTYPE html>
<heml>
<head>
    <meta charset="utf-8">
    <title>java script</title>
</head>
<!--對事件的反應-->
<body>
    <script>
        document.write("按鈕");
    </script>
    <button type="button" onclick="alert('Welcome!')">click</button>
</body>
</heml>